Method of truing millstone paint-staffs



(No Model.)

W. LEHMA NN. Method of Trueing Millstone Paint Staffs.

ATTORNEY N. PE ERS. PHOTO-LITHOGRAPHER, WASHINGT ON. 0 C4 UNITED STATES PATENT OFFICEO WILLIAM LEHMANN, OF MILWAUKEE, WIS OONSIN.

METHOD OF TRUING MILLSTONE PAlNT-STAFFS.

SPECIFICATION formingpart of Letters Patent No. 230,881, dated August 10, 1880. Application filed April 2, 1880. (No model.)

To all whom it may concern:

Be it known that I, WILLIAM LEHMANN, of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Methods of Truing Millstone Paint-Staffs; and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

lWIyinvention relates to a staff to be employed in practicing theimproved method of truingthe face of millstone paint-stafis described in the specification of a patent granted to me therefor January 7, 1879 and it consists in constructing the staff of wood with a true plane surface, except at the center, where it is cut away sufficiently to compensate for the expansion which occurs at that point when the wet paint or color is applied thereto. In the accompan yin g drawing that staff is denoted by A.

I have found in the use of my invention above named that the liquid paint (Venetian red and water) usually employed to redden the central portion of the staff causes that portion of the wood to which it is applied to swell or puff out, and thereby the central or painted portion of the staff protrudes beyond its remaining surface, sometimes to a distance as great as the thickness of two sheets of ordinarily thin writing-paper. This is a very great disadvantage, because when the staff is in this condition an inequality in the surface of the millstone less than the extent of this protuberance is not detectable by the use of the staff in the manner set forth in the beforementioned patent.

It has, in the art of milling as at present practiced, become of the greatest importance to be able to detect and correct even so apparently slight a variation as this. I accomplish this by scraping, sandpapering, or rubbing away the surface of the stafl' where paint is to be applied to such a depth that when it swells under the paint the surface of the staff applied to the stone shall be perfectly true. In doing this I first make the staff A perfectly true by application to the proof-staff andthe use of the other well-known means. I then drive the small tacks a a b I) b 1) into the side of the stafl', the side bearing the letter A being the face of the staff. b b b b mark the limits of the central portion of the staff to which, in use, paint is to be applied, as is described in my former patentalluded to. a a are placed about half an inch outside thoselimits. Paint should now be thoroughly applied to all that portion included between a a, and after the surface has swelled out it should be rubbed, scraped, or sandpapered down until the entire surface of the staff is perfectly true. When this is accomplished the face of the staff will be depressed between a a when dry, but will be flush or even with the rest of the face when wet or painted.

The space between a and I) b is left in order to prevent the paint lapping over upon the raised portion of the staff and causing that to swell also.

It will thus be seen that the concave center compensates for the swelling caused by the paint, and insures perfect accuracy in the staff when used.

I claim 1. The wooden staff for truing millstones, haviu g an otherwise true face slightly recessed in the middle, in the manner and for the purpose substantially as described.

2. The herein-described method of construct ing a wooden staff for truing millstones, consisting in first forming the same with a true plane face, and then painting or dampening it at the center to cause the grain to rise at that point, and, finally, truing the face throughout its entire length While the center is in the expanded or elevated state, as and for the purpose described.

' In testimony that I claim the foregoing as my own I affix my signature in presence of two witnesses. I

WILLIAM LEHMANN.

Witnesses:

E. H. BOTTUM, G. T. BRYANT. 

